July 22, 2014

Summery dune

A piece of Mars: Last December I blogged about a picture of a sand dune taken in early northern spring. This is the same dune, without frost, now that summer has come to the northern hemisphere and all the frost […]
July 8, 2014

How hills change dunes

A piece of Mars: Using dunes to interpret the winds can be a tricky business. Here’s one reason why: most of the dunes here go from the upper left to lower right. But the ones inside the funky oblong crater […]
July 1, 2014

Where is Curiosity on her 1 Mars year anniversary?

A piece of Mars: Curiosity has been trolling around on Mars for one martian year, so I think it’s time I posted an update on where it is and what it’s seeing. Right now (late June 2014), the rover is […]
June 24, 2014

In the lee

A piece of Mars: This crater (290 m or 950 ft across) is crawling with all sorts of ripples and dunes. The wind mainly blows from the top to the bottom of the frame, and it is responsible for the […]
June 18, 2014

Swirly rocks

A piece of Mars: Never mind the 4 m (13 ft) boulders that have fallen downslope, or the rippled sandy surfaces here. Look at those bright swirls in the ground. Those are the former interiors of sand dunes, which were […]
June 13, 2014

Whither the wind

A piece of Mars: Which way did the wind blow here? You can tell by looking at the dune and its ripples. The slip face (the avalanching slope of the dune) faces downwind, so the strongest wind here mainly blows […]
June 2, 2014

The always-changing landscape

A piece of Mars: Over time, windblown sand can wear down a surface. This isn’t so common on Earth, where water, ice, and life are more likely to change the landscape, but it’s typical of many places on Mars. Here, […]
May 26, 2014

Flow

A piece of Mars: This is a bit of the flank of Arsia Mons, one of Mars’ great volcanoes. The big changes in topography are ancient relics of erosion by lava and great tectonic pulling. What I like is that […]
May 19, 2014

Debunking Hoagland’s “Glass Worms” with HiRISE

A piece of Mars: Several years ago, a guy named Richard Hoagland claimed that some parallel linear features on Mars looked like the ridges of a transparent earthworm, calling these things “glass worms”. Phil Plait debunked it nicely, but Hoagland […]